The long-term goal of this research application is to identify how the amygdala influences auditory perception and function. Specifically it focuses on identifying the effect(s) of amygdalo-collicular projections on cells in the inferior colliculus (IC). The amygdala is thought to play a major role in functions such as emotion, memory, and learning. How such circuitry could influence auditory processing is unknown. The amygdalar projection to the IC influences auditory perception due to previous auditory experience or the emotional state of the animal. The experiments in this application will identify: 1) the physiological response of amygdalar and amygdalo-collicular cells; 2) the morphology and termination pattern of amygdalar projections; and 3) what specific effect(s) amygdalo-collicular projections have on IC cells. This information will contribute to a greater understanding of how descending systems modulate and control auditory processing. It may also provide information about how the auditory system affects the normal aspects of mood, emotion, memory, communication, and learning, as well as pathological conditions associated with tinnitus, depression, bipolar disorders, panic disorders, Alzheimer's, and learning disorders. [unreadable] [unreadable]